Electric range



Dec. 15, 1936. A. BARNSTEINER ELECTRIC RANGE Filed Feb. 21, 1954 2 Sheets-Sheet 1 WITNESSES INVENTOR r4 /f0/7$ Burris/camel:

TATTORNEY Dec. 15, 1936. A BARNSTEINER 2,063,975

ELECTRIC RANGE File d Feb. 21, 1934 2 Sheets-Sheet 2 WITNESSES: INVENTOR 5Q A/fbns Barnsfe/nen.

:IJ BY Z414 g 44 W ATTORNEY Patented Dec 15, 1936 UNITED STATES PATENT OFFICE Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of Pennsylv Application February 21, 1934, Serial No."112,319

1 Claim.

My invention relates to electric ranges and has particular relation to the design of and arrangement of parts in domestic ranges which utilize surface exposed heating units of the low- 5 voltage high-current type.

Such low-voltage range heating units, which may conveniently be energized through suitable transformers from the usual residence-potential power circuits; possess a number of advantages a proper appreciation of which it now appears maycause them to supplement or even replace the conventional line-voltage devices which at the present time are so extensively employed in cooking-device applications.

In a low-voltage unit, for example; little or no insulation is required on the heat-producing conductor and a correspondingly higher efficiency of thermal conductivity to receptacles and other materials may be realized. Likewise. the energizing voltage may be reduced to completely non-dangerous values with an attending elimination of all possibility" of electrical shock to the-housewife or other user. In addition, the

body or cross-section of the heavy-current heat producing conductor may be made sufiiciently large to afford mechanical ruggedness of an unbreakable order and to prevent appreciable diminution due to a flaking off of the outer material at the high operating temperatures. 'As a resuit, the life of such a unit is practically unlimited. Furthermore, the presence of a transformer, the ratio of which may readily. be

' changed by winding-tap control in the energizing circuit, makes practical a variation of supp voltage in'a large number of steps and thereby facilitates heat-intensity adjustment.

v The present invention concerns improvements which will make low-voltage cooking ranges more practical.

40 One object of the invention is to provide improvements in the structures of domestic ranges of the low-voltage heating unit type.

Another object of the invention is to make use of the heat losses' dissipated by the step-down transformers in the heating unit supply circuits.

derstood through the following description of specific embodiments when taken in conjunction with the accompanying drawings, in which:

Figure 1 is a top or plan view of a domestic range structure, incorporating a plurality of low- 5 voltageheating units, constructed in accordance with my invention;

Fig. 2 is a view in front elevation of the range structure of Fig. 1;

Fig. 3 is a sectional view taken on line III-III of Fig. 2 showing one preferred positioning of the step-down unit-supply transformers within the range structure;

Fig. 4 is an enlarged top plan view of the single spiral conductor heating unit comprised by the range structure of Figs. 1 to 3;

Fig. 5 -is'a section view taken on line V--V of Fig. 4;

Fig. 6 is an enlarged top plan view of the double spiral .conductor heating unit comprised by the range structure-of Figs. 1 to 3;

Fig. 7 is a section view taken on line VIIVIJ.' of Fig. 6; and

Fig. 8 is a diagrammatic representation of one form of heat-adjusting control circuit which may be utilized by the range heating units.

Referring to the drawingsgand particularly to Figs. 1, 2 and 3 thereof, the domestic range there illustrated comprises a horizontal cooking platform It, on the top of which are arranged a plurality of separate surface-type heating units i2, ll, Ii and Il. .Each of these units is supplied with the required low voltage energizing current through a step-down transformer 20, shown in Fig. 3, which is connected with the conventional linevoltage domestic power circuit designated by conductors It. To control and adjust the intensity of the heater energization, each unit is further provided with a control switch 24, the actuating knob 26 of each of which protrudes through the front of the range structure in the manner shown.

The illustrated positioning oi the several heating units in a straight line near the front of the cooking platform is of advantage in any domestic range in that it makes all of the units uniformly accessible and eliminates the necessity of reaching over a unit to gain access to any of the others. It is of further utility in the low-voltage heating unit combination now under consideration in that it allows a sufllcient area of unoccupied cooking platform behind the units to permit dishes,,receptacles, or other materials to be placed directly thereon and to receive preliminary warming from the heat dissipated by the unit ener- 6i gizing transformers which are preferably mounted there-beneath. In practice, the heat so dissipated is of appreciable magnitude and by mounting the transformers in the manner shown un derneath the rear portion of the cooking platform this dissipated heat may be utilized to advantage. A further feature of my invention resides in the provision in the lower front portion of the range structure of a receptacle storage compartment 28, access to which is gained through the opening of doors 30, shown as being hinge-mounted. By providing in this compartment means, indicated in the form of a shelf member 32, for supporting receptacles near the upper portion thereof in relatively close proximity to the transformers 20, further advantage of the heat dissipated by these transformers may be taken in the warming of dishes or materials set uponthis shelf.

Considering now the individual heating units themselves, each, as is best indicated by Fig. 3, receives the required low-voltage high-amperage energizing current from the secondary winding 36 of a transformer 20 through suitable low resistance type bus bar connections 38 and 39. The primary winding 40 of this transformer is, as before mentioned, connected to receive energizing current from the power supply circuit 22. As shown, this connection is established through a multi-conductor cord 42 which enters the back of the range. Preferably, the transformer should i have the illustrated separate and electricallyinsulated primary and secondary windings in order that the low-voltage heater circuit may be completely isolated from the higher potential supply circuit, the voltage of which is seldom less than 110 or 220 volts.

""In order that the heat intensity may be adjusted the primary winding 40 ofthe transformer is provided with a plurality of taps H to which the energizing circuit is selectively connected through the actuation of the control switch 24. One preferred manner of control connection is indicated in Fig. 8 in which this switch is represented as comprising a blade member 46 which is arranged to selectively route the energizing current from power circuit 22 among the taps 44 of the primary winding 40, to thereby change the ratio .of transformer 20 and correspondingly vary the voltage supplied by the secondary winding 36 to the range heating unit, represented at 48 in Fig. 8. When the blade occupies the extreme upper or off po sition shown, the transformer, and hence the heating unit, is completely deenergized. A downward advancement of the blade to the first ac tive position energizes the unit at the minimum voltage. Further advancement raises this voltage in progressive steps until the maximum, effected when the blade is in the extreme downward position, is supplied.

The two heating units l6 and i3 represented as occupying positions at the right portion of the range structure are of the parallel heat-producing conductor type more completely disclosed and claimed in a copending application, Serial No. 712,342, by E. H. Lockwood, filed February 21, 1934, and assigned to the same assignee as this invention. No detailed description of them is accordingly here given except a mention of the fact that their maximum energizing voltages may be as low as one or two volts and that no insulation whatever is required on their exposed surfaces. The two heating units l2 and [4 represented at the left of the complete range structure are of the single or series connected heat producing conductor type, the improved designs of which form a part of the present invention.

Considering first the heating unit I, the details of construction of which are most clearly shown by the enlarged views of Figs. 4 and 5, this unit comprises a heat producing conductor 52 arranged in the form of a spiral, the center or starting point of which terminates in the energizing current supply bus 33, before discussed in connection with Fig. 3, and the outer or ending point of which terminates in the other supply bus 39. To support the convolutions of the heating conductor intheir proper relation in the common horizontal heater-area plane, I utilize a member 58 of refractory material, which member is provided with a peripheral edge projection 60 which engages with the edges of the heating unit opening in the cooking platform Hi, to constitute a support for the entire assemblage.

Each of the individual convolutions of the heat-producing conductor 52 is accommodated by a slot 62 in the upper or exposed face of this refractory member 58. The depth of this slot may, as shown in Fig. 5, be slightly less than the diameter of the conductor, in order that direct contact by receptacles or materials placed upon the heating unit may be established, or the slot may be deepened to the extent that-the conductor occupies a position below the exposed surface of the supporting member 53. This latter type,of construction is exemplified by the showing of Fig. 7.

Regardless of the slot depth, I have found that with the illustrated spiral arrangement of the heating conductor, the energizing current, which may be of the order of several hundred amperes, sets up a powerful magnetic field which very strongly attracts magnetic material receptacles or other objects placed thereon. This attraction is an advantage in that it more intimately draws the receptacle into contact with the heat producing conductor, and thereby raises the efliciency of heat transfer. It will be understood. of course, that when this characteristic is taken advantage of the design of the heating unit must be such that the voltage required for proper energization is of an exceedingly low' value, otherwise local or shunting circuits may be set up through the receptacle material. If it is desired to further safeguard against this possibility, the heating conductor 52 may be coated with a thin layer of insulating material or the conductor may be positioned slightly below the surface of the refractory supporting member 58. In either case, the magnetic attraction will serve to draw the receptacle into more intimate contact with the material which supports it and will, in this manner, increase the thermal conductivity thereto.

In cases in which it is desired that this magnetic attractive effect be eliminated, the modifled spiral design shown in Figs. 6 and 7 may be utilized. In this design instead of arranging the heat producing conductor in the form of a single spiral, a double spiral or loopingback arrangement is utilized. Thus, as is indicated in Fig. 6, one of the supply buses 38 is joined with the central or starting end of one of the spirals 64 which advances outwardly to the point 66 where it Joins with the second spiral 68 which returns inwardly to the center of the assemblage where it terminates in a connection with the other supply bus 39. As a result of this double or looping-back arrangement, the magnetic field otherwise produced is completely neutralized and the before explained attractive effects are completely eliminated.

Although I have shown and described certain specific embodiments of my invention, I am fully aware that many modifications thereof are possible. My invention, therefore, is not to be restricted except insofar as is necessitated by the prior art and by the scope of the appended claim.

I claim as my invention: In an electric range structure, the combina- 10 tion of a cooking platform, a plurality of heating units mounted thereon in line near the front thereof, a. transformer electrically connected to one of the units and mounted underneath the rear portion of the platform, a receptacle storage compartment in the front of said structure beneath said platform and in front of said transformer, and a. control switch for said unit mounted on the front'of said struc- I 

